1968 Ford Mustang carburator adjustment

first thing you do is make sure all your ignition stuff is right, like dwell and timing. then shut the engin off and turn both screws in until the touch lightly. Not like tightening a screw up. then back the screw out 1 and 1/2 turns. Put a vacuum guage on the intake manifold. If not available hook up a tach. then adjust the screws one at a time to either the highest vacuum reading or the highest RPM. If the idle goes to high, then readjust the idle back down and start over.